1. Field of the Invention
The present invention relates to a treatment device that is inserted through a natural orifice of a human into a duct cavity.
2. Description of Related Art
Endoscopic retrograde cholangiopancreatography (ERCP) has been known as a method of diagnosing abnormalities of the pancreas, gallbladder, or bile ducts. In ERCP, a catheter is inserted through the papilla of the duodenum, and then a contrast agent is injected directly through the pancreatic or bile ducts, thereby allowing X-ray images to be acquired.
If the entrance of the papilla is narrow or the lining of the bile duct is curved, it is difficult to insert the catheter into the bile duct. Excessive stabbing of the entrance of the papilla with the catheter may cause a mucous membrane edema, unnecessarily narrowing the entrance. Moreover, when the catheter is thrust into a submucosa through the mucous membrane when stabbing the entrance with the catheter, insertion of the catheter becomes more difficult. When a contrast agent is injected in a state that the catheter is thrust into the submucosa, the contrast agent will be injected into the submucosa so that the mucous membrane is inflated to further obstruct the entrance of the papilla. Moreover, when the edema happens or the contrast agent is injected into the submucosa to obstruct the orifice of a pancreatic duct, draining of pancreatic juice is interrupted, resulting in increasing possibility to develop pancreatitis. As another method, there is a method in which a guidewire having a flexible distal end that is relatively easily bent is protruded by about 2 to 3 mm from the distal end of the catheter to access the bile duct. Since the distal end of the guidewire is flexible but narrow, force is likely to concentrate on a single point and therefore excessive stabbing may cause an edema or the guidewire to be thrust into the submucosa. Thus, in order to prevent pancreatitis, it is necessary to decrease the risk of the edema or the puncturing of the mucous membrane as much as possible.
In the conventional procedures, the distal end portion of the catheter where an opening of the lumen for passing a contrast agent is rounded as much as possible so that the distal end portion of the catheter does not cause the edema or the puncturing of the mucous membrane.